I sometimes get on a nostalgia kick and start playing the older games. I played RYS (the three games that still work) over the summer a bunch to make teams to finally beat Stadium and Stadium 2, but now that I've done that, completed my Pokedexes, etc, I'm not sure how frequently I'll use them. I have started a couple of new games on ROMs since getting home for Christmas break, but I'm afraid to do too much on the older games for fear that the batteries will die and kill all of my efforts.
I did get some new batteries for my games, though, so at some point I'd like to start repairing them (starting with G, C, and maybe B). I don't think that those games will ever be dead for me, but I probably won't play them as much as I used to.